The investigatory technique of bronchoalveolar lavage (BAL) has become one of the most valuable research tools for studying inflammatory mechanisms in a wide range of diseases that affect the lungs and airways in humans, and several thousand peer review papers are published each year. In addition, cytological and microbiological testing of BAL samples are of established value for assisting in clinical diagnosis and management of many lung diseases, and these procedures are available routinely in most modern specialist respiratory centres. Yet despite its undoubted value, the interpretation of BAL findings is still hindered because the procedure cannot be precisely standardized. In particular, there is still no satisfactory method of determining the dilution factor during lavage. This prevents accurate quantification of all components in BAL fluids and causes especial difficulty in interpreting the results of measurements of soluble acellular components. A number of Task Force reports have been published that have provided guidelines for the clinical application of BAL, and on technical aspects mainly related to evaluation of cells and other cytological features [1±4]. However, no guidelines are currently available for evaluation of acellular components, nor are any firm recommendations available for standardization of BAL procedure. The purpose of this editorial is to inform that this omission is now addressed by a new report of a European Respiratory Society (ERS) Task Force which is currently being published in the European Respiratory Review [5]. This Report provides a comprehensive review of the current status of techniques for measurement of acellular components in human BAL samples, and gives guidelines and recommendations to define standard procedures for the general conduct of BAL. It updates previous guidelines and gives recommendations on how to comply with the increasing demands for more effective quality control. The Task Force was established by the BAL Scientific Group of the ERS in September 1995. The authors were privileged to be the task force co-ordinators and editors of the report, to which 49 authors and 21 invited reviewers from 15 countries contributed. It contains a series of detailed critical reviews which give recommendations according to the consensus view on 17 topics. These include three sections concerned with the general problems of BAL standardization [6±8] and one section dealing with the special problems relating to children [9]; while the remaining 13 sections provide detailed information on specific considerations that apply to the measurement of different categories of specific components including pulmonary surfactant components [10], immunoglobulins [11], proteases and antiproteases [12], angiotensin-converting enzyme [13], antioxidants, oxidants and oxidation products [14], lipid mediators [15], cytokines [16], soluble adhesion molecules [17], markers of fibrosis [18], granulocyte derived markers [19], tumour markers [20], markers of cell death [21], and other acellular components [22]. Those beginning work on lavage will find information about problems and pitfalls and how best to avoid them, while those experienced in the field will find comprehensive critical reviews to assist with selecting optimal approaches. All are encouraged to agree to the recommendations for better standardization procedures, in order to facilitate multicentre studies and the clearer comparison of findings between different workers to aid clinical interpretation.

Early BAL studies were focused mainly on defining the predominant types of inflammatory cells associated with different lung diseases. Despite concerns about the …